Process of sealed switch manufacture



June 18, 1968 N. INSLEY 3,338,463

PROCESS OF SEALED SWITCH MANUFACTURE Filed May 5, 1965 77am A alelmz'nm,

ArroeMsYs United States Patent 3,388,463 PROCESS OF SEALED SWITCH MANUFACTURE Norman Insley, Nanuet, N.Y., assignor to C. P. Clare & Company, Chicago, 11]., a corporation of Delaware Filed May 3, 1965, Ser. No. 452,725 7 Claims. (Cl. 29-622) ABSTRACT OF THE DISCLOSURE Sealed magnetic reed switches are made by a method in which the operating gap between the contact structures is set by a gauge portion formed on one of the contact structures. The contact structures are inserted into a glass housing and moved to an adjustingportion determined by the engagement of the contact structures along the gauge portion. This sets the operating gap. The contact structures are then shifted to an operating position in which the contact areas of the contact structures are aligned with each other by relative movement in a direction that maintains the preset gap setting in the operating position, the gauged portion is not in engagement. The contact structures are sealed in the glass housing in the operating position.

This invention relates to a sealed switch construction and, more particularly, to a new and improved sealed switch unit and method of manufacturing this switch unit.

One of the problems present in the automatic manufacture of scaled magnetic reed switches is that of maintaining the desired air gap between certain of the switch components within a tolerance range small enough to prevent appreciable changes in the predicted operating characteristics of the switch. This generally can be done with those sealed switch units having only a pair of magnetic elements that are selectively moved into and out of engagement by an applied field, although it does require careful control over manufacturing techniques and the use of precision locating components in the automatic manufacturing equipment which are located externally of the switch housing. This type of sealed switch usually is one in which one magnetic element is sealed in each end of an elongated housing. This permits the relative positions of the overlapped portions of the elements which are disposed within the housing to be accurately controlled by locating apparatus located externally of the housing.

However, the problem of setting and maintaining the operating gap in sealed switches providing a transfer contact action or having plural contacts is much more ditficult. This type of switch commonly comprises an elongated housing, in one end of which two contacts are sealed. A flexible magnetic armature is sealed in the other end of the housing and includes an inner end portion disposed within the air gap between and in an overlapped relation with the contacts. When this type of switch is manufactured, the operating gap between the two contacts is set by inserting a gauging fixture into the housing to be positioned between the contacts and by maintaining the gauging fixture in its interposed position during the formation of a seal in the end of the housing through which the contacts project. This gauge is then removed, the armature is inserted and properly positioned relative to the contacts, and the second seal is formed in the other end of the housing. This use of the gauging fixture makes it quite diflicult to automate the production of scaled switch units providing transfer contacts with the result that the cost of these switches is frequently greater than would be desirable.

Accordingly, one object of the present invention is "ice to provide a new and improved method of making sealed switch units.

Another object is to provide a method of making transfer contact sealed switches capable of being carried out in automatically operating machines.

A further object is to provide a method of making sealed switches in which one of the components of the switch is manipulated to provide a gauge for setting an operating gap in the switch.

Another object is to provide a method of making sealed switches of the type including a contact and a magnetic armature in which the armature includes a gauging portion which is manipulated to control the relative location of the armature and contact within the switch housing.

A further object is to provide a method of making sealed switches in which the armature of the switch is placed in a first position to properly position one or more contacts during the formation of the contact seal and is then moved to a different position in which the armature provides its normal contacting function, at which time the armature seal is formed.

A further object is to provide a method of making transfer contact sealed switches in which the switch armature is used as a gauging means.

A further object is to provide a new and improved sealed switch construction.

Another object is to provide a sealed switch construction including an armature having both gauging and contacting areas.

A further object is to provide a new and improved sealed switch providing transfer contacts in which the armature includes both a contacting area and gauging portion having a pair of gauging surfaces extending generally parallel to the contacts of the switch.

In accordance with these and many other objects, an embodiment of the invention comprises a sealed switch construction having an elongated insulating or glass housing in one end of which a pair of make and break contacts or terminals are sealed, the break contact including a non-magnetic portion. A flexible armature is sealed in the other end of the elongated housing and includes a contacting area at its inner free end normally biased into engagement with the break contact and adapted, upon application of an operating field across the operating gap between the contacts, to move out of engagement with the break contact and into engagement with the make contact.

When the sealed switch is manufactured from an insulating or glass tube, the make and break contacts are inserted in one open end of the glass tube in generally parallel and spaced positions. The armature is inserted through the other end of the glass tube and is disposed so that a gauging portion adjacent but spaced inwardly from the contacting areas at the free end of the armature is interposed between and engages the make and break contacts. These contacts are biased into engagement with opposite sides of the interposed gauging portion of the armature to precisely set the desired operating gap in the switch. A seal is then formed in the contact end of the glass tube, as by heating, with the gauging portion of the armature interposed between the contacts so as to positively maintain the desired operating gap. When this seal has been completed, the armature is retracted so that the contacting surfaces are now interposed between the contacts, and a seal is formed in the other end of the glass tube to mount the armature on the housing, preferably with the armature engaging the break contact. In this manner, the operating gap between the make and break contacts is positively set without requiring the use of a gauging fixture which must be inserted and removed from the housing and permits the formation of the transfer contact sealed switch by the use of automated equipment.

Many other objects and advantages of the present invention will become apparent from considering the following detailed description in conjunction with the drawings in which:

FIG. 1 is a sectional view of a sealed switch embodying the present invention;

FIG. 2 is a schematic view illustrating the components of the sealed switch during the formation of a seal for the switch;

FIG. 3 is a sectional view showing the elements of the switch during the formation of an armature seal;

FIG. 4 is a sectional view taken along line 44 in FIG. 2; and

FIG. 5 is an enlarged perspective view of an end portion of an armature included in the sealed switch.

Referring now more specifically to FIG. 1 of the drawings, therein is shown a sealed switch unit which embodies the invention and which is indicated generally as 10. The switch includes an elongated insulating or glass housing 12 in one end of which a pair of contact structures 14 and 16 are sealed in generally spaced and parallel positions with their inner ends disposed within an axial opening or cavity 18 formed by the housing 12. A flexible magnetic armature structure 20 is sealed in the other end of the housing 12 and includes an inner end portion disposed within the cavity 18 with a contacting portion 29a disposed in an operating air gap 22 defined between the inner ends of the contact structures 14 and 16 and engaging the contact structure 16 which provides a break contact. The break contact structure 16 includes a non-magnetic portion so that upon the application of a magnetic field, the armature 20 is deflected to move the contact portion 20a out of engagement with the break contact structure 16 and into engagement with the make contact structure 14. The armature 20 is returned to its normal position engaging the break contact structure 16 when the applied field is removed. Thus, the sealed switch unit provides a transfer contact in which the common armature 20 selectively engages the contact structures 14 and 16 under the control of an applied operating field.

The break contact structure 16 includes an outer magnetic terminal or pin 16a which is shown as having a circular section, to the inner end of which a contact or contact member 16b is secured. The surface of the contact 16b facing toward the contact portion 20a of the armature 20 can have any suitable configuration, but preferably is uniplanar as shown in the drawings. The contact 16b is formed of non-magnetic material. The

make contact structure 14 includes an outer terminal or I pin 14a, which is shown as being circular in section, to the inner end of which a contact or contact element 14b of magnetic material is secured. The inner surface of the contact member 14b facing inwardly toward the operating gap 22 can be of any suitable configuration, but preferably is uniplanar as illustrated in the drawings.

The gap 22 between the magnetic contact 14b and the non-magnetic contact 16b or, more specifically, between the contact 14b and the contact portion 20a of the magnetic armature 20 determines the operating characteristics of the switch 10 and must be maintained constant to insure the production of the switches 10 of uniform characteristics. Since the thickness of the contact portion 20a of the armature 20 can easily be maintained constant and since the contact portion 20a is normally biased into engagement with the non-magnetic contact 16b the space between the contacts 14b and 16b effectively controls or sets the operating gap 22.

The magnetic armature 20, which can be formed in a number of different configurations, is illustrated in the drawings as being formed of a wire, pin, or rod of magnetic material of circular section which has been flattened at its outer end to provide a terminal portion 20b. An intermediate portion of the circular section on the armature 20 is sealed in one end of the glass housing 12. To

impart flexibility to the armature 20, a portion 20c of this armature is flattened at a position interposed between the seal and the contact portion 20a at the free end. The contact portion 20a at the free end of the armature 20 is provided with a pair of opposed surfaces 24 whose configuration is set in accordance with the configuration of the contacts 14b and 16b. In the illustrated construction 10, the contact portion includes the pair of generally uniplanar opposed, and parallel surfaces 24 which overlap the uniplanar surfaces on the contacts 14b and 16b and are adapted to be moved into alternate engagement therewith. The thickness of the armature 20 intermediate the two surfaces 24 is substantially less than the transverse dimension of the gap 22 separating the contacts 14b and 16b. If desired, the mating surfaces of the contacts 14b and 16b and the surfaces 24 can be provided with a layer of contact material, such as gold.

To provide means for precisely setting the operating gap 22 without requiring the introduction of gauging fixtures into the cavity 18 of the housing 12 during the manufacture of the switch 10, the armature 20 is provided with a gauging portion 20d including a pair of generally uniplanar and parallel surfaces 26 formed on opposite sides of the free end of the armature 20 spaced immediately inwardly from the contact portion 211a. In manufacturing the armature 20, it is possible to precisely control the thickness of the armature between the two surfaces 26 or the spacing between these two surfaces so that it exactly equals the transverse dimension of the gap 22 between the contact elements 14b and 16b.

When the switch It) is to be assembled, a glass tube forming the housing 12 is inserted into the axial openings in a pair of heating elements or coils 30 and 32 so that the upper end of the tube 12 is encircled by the heating element 39 and the lower end is encircled by the heating element 32. The two contact structures 14 and 16 are then inserted through the open end of the tube 12 and disposed in a position approximating their desired position in the switch ltl. The armature 26 is then inserted through the open upper end of the tube 12 and advanced to an adjusting position in which the gauging portion 20d of the armature is interposed between the contacts 14b and 16b with the surfaces 26 disposed in generally parallel relationship to the uniplanar inner surfaces of the contacts 14b and 16b (FIG. 2). The contact structures 14 and 16 are then adjusted so that the inner uniplanar surfaces of the contacts 14b and 16b are pressed or biased into engagement with the parallel surfaces 26 of the gauging portion 20d of the armature. The heating element 32 is then rendered effective to soften the glass at the lower end of the tube to form the lower seal as shown in dot-and-dash outline in FIG. 2 of the drawings.

Following the completion of the formation of the first or lower seal, the armature 20 is retracted or moved longitudinally or axially relative to the tube or housing 12 from the adjusting position shown in FIG. 2 to the position shown in solid line in FIG. 3. In this operating position, the gauging portion 20d of the armature 20 is displaced from the adjusting position interposed between the contact elements 14b and 16b, and the contact portion 20a is now interposed between these contacts with the surfaces 24 disposed in a generally parallel relationship to the uniplanar inner surfaces of the contact members 14b and 16b. The armature 20 is then displaced to the position shown in dot-and-dash outline in FIG. 3 so that the right-hand surface 24 on the contact portion 20a is moved into abutting relation or engagement with the inner surface of the non-magnetic contact 16b. This adjustment is made to provide proper overlap between the armature 20 and the contacts and proper contact pressure between this armature and the non-magnetic contact 16b. The upper heating element 30 is then energized or rendered effective so that the glass at the upper end of the tube or housing 12 is softened to form the upper or armature seal which is shown in dot-and-dash outline in FIG. 3. When the glass forming the upper and lower seals has suitably solidified, the completed switch is removed from the heating elements 30 and 32.

The method embodying the present invention described above is one that is capable of being carried out in auto matic switch making machines of the general type shown, for instance, in the copending application of Harry Chanowitz et al., Ser. No. 309,449, filed Sept. 17, 1963, nOW Patent No. 3,282,670, in which the terminals and glass envelope are automatically supplied to positioning chucks located on expanding and contracting assembling heads mounted on a continuously moving turntable. With apparatus of this general type, it is possible to closely control the position of the armature including the gauging portion 20d, and this close control of the armature 20 including the gauging portion 20d provides means for aligning the armature in the center of the fixed contacts 14b and 16b, for setting the contact gap 22, for adjusting the magnetic overlap between the surface 24 on the contact portion 20a of the armature and the mating surface of the break contact 16b, and the setting of the back contact pressure. The fact that the gauging portion 20d on the armature 20 avoids the need for external gauging fixtures which must be inserted into the tube 12 during the assembly operation facilitates and permits the automatic assembly of the switch 10 and obviates the need for time consuming and expensive manual assembly operations.

Although the method embodying the present invention has been described in relation to the sealed switch 10 in which the armature 20 normally engages the break contact 16b, it can also be used with and in the manufacture of a center stable switch in which the contact portion 20a is equally spaced from the two magnetic contacts 14b and 16b and normally occupies the position shown in solid line in FIG. 3 of the drawings. In this type of construction, the armature 20 is operated into engagement with the contacts 14b and 1612 by applying magnetic biases to the gaps between the armature 20 and the contacts 14b and 16b and controlling the polarity of the signal applied to the operating winding.

Although the present invention has been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall without the spirit and scope of the principles of this invention.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. A method of making a sealed switch unit of the type having a make contact and a break contact carried on one end of an elongated housing and adapted to be alternately engaged by a common armature carried on the other end of the housing, the armature having an end portion of two different thicknesses, which method comprises the steps of inserting the make and break contacts into one end of the elongated housing in spaced positions,

inserting the armature into the other end of the elongated housing with an end portion of one of said two thicknesses interposed between the make and break contacts in an adjusting position, adjusting the make and break contacts to bear against the interposed end portion of said one thickness to set a gap between the make and break contacts having a value substantially equal to said one thickness,

forming a seal in said one end of the housing to mount the adjusted make and break contacts in fixed positions,

moving the armature from the adjusting position to an operating position to place the end portion of said other thickness which is less than said one thickness in engagement with the break contact,

and forming a seal in said other end of the housing to mount the armature on said other end of the housing in said operating position with the end portion of said other thickness engaging the break contact. 2. A method of making a sealed switch unit of the type having spaced first and second contacts carried on one end of an elongated housing and adapted to be alternately engaged by a common armature carried on the other end of the housing, the armature having an end portion of two different thicknesses, which method comprises the steps of inserting the first and second contacts into one end of the elongated housing in spaced positions,

inserting the armature into the other end of the elongated housing with an end portion of one of the two thicknesses disposed in an adjusting position between the first and second contacts,

adjusting the first and second contacts to bear against the interposed end portion of said armature of one thickness to set a gap between the first and second contacts having a value of substantially equal to said one thickness,

forming a seal in said one end of the housing to mount the adjusted first and second contacts in fixed positions, moving the armature from said adjusting position to place the end portion of the other thickness which is less than said one thickness in an operating position interposed between the first and second contacts,

and forming a seal in the other end of the housing to mount the armature on the other end of the housing and fix said other thickness in said operating position.

3. A method of making a switch having a pair of contact making structures, each of the structures having a contact area and at least one of the structures having a gauging portion spaced from its contact area, which method comprises the steps of moving the contact making structures into an adjusting position in which the two contact areas are not adjacent each other,

moving the two contact structures at the adjusting position into engagement at said gauging portion to set a predetermined gap between the two contact areas measured in a given direction,

producing relative movement between the two structures in a direction generally transverse to said given direction while maintaining said predetermined gap between the two contact areas to relatively move the two structures including said gauging portion from the adjusting position to an operating position in which the first and second contact areas are located in an overlapped relation spaced from each other by said predetermined gap and the gauging portion is moved out of engagement in said operating position,

and fixing the positions of the two structures in said operating position to provide a switch in which the contact areas of the contact making structures are spaced from each other by said predetermined gap and are disposed for movement into and out of engagement with each other.

4. A method of making a sealed switch unit of the type having a contact structure carried on one end of an elongated housing with a contact area adapted to be engaged by the contact area on an armature structure carried on the other end of the housing, at least one of the structures having a gauging portion, which method comprises the steps of positioning the contact structure within the elongated housing through one end of the housing,

inserting the armature structure into the other end of the elongated housing to a position disposed in an overlapping relation with the contact structure, moving the structures into an adjusting position in which the structures are in engagement at said gauging portion so that the gauging portion is in a position interposed between the armature structure and the contact structure to set a predetermined gap between the contact areas, said gap being measured in a given direction,

forming a seal in an end of the housing while maintaining the predetermined gap between the contact areas, displacing the armature structure and the contact structure relative to each other in a direction transverse to said given direction While maintaining said predetermined gap between the contact areas to move the armature and contact structures from the adjusting position to an operating position with the gauging portion being moved out of its interposed position in the operating position and the contact areas of the armature and contact structures being moved to overlap positions in the operating position,

and forming a seal in the other end of the housing while maintaining the structure in said operating position to complete the mounting of the armature and contact structures on the opposite ends of the housing.

5. The method set forth in claim 4 in which the step of displacing the armature and contact structures relative to each other includes moving the armature structure generally axially along the elongated housing from the adjusting position to the operating position.

6. A method of making a sealed switch unit of the type having generally parallel and uniplanar make and break contact surfaces supported at one end of an elonhousing and adapted to be alternately engaged by a common armature carried on the other end of the housing, the armature having a contact portion and a gauging portion formed of two parallel and opposite surfaces spaced a given distance from each other, which method comprises the steps of disposing the make and break contact surfaces within one end of the elongated housing in spaced and generally parallel positions, inserting the armature into the other end of the elongated housing into an adjusting position to move the parallel surfaces of the gauging portion between the make and break contacts, moving the make and break contact surfaces and the parallel surfaces of the gauging portion into engagement to set a gap of said given distance between the make and break contact surfaces, forming a seal in said one end of the housing to mount the make and break contact surfaces in fixed positions with the gauging portion disposed between and engaging these surfaces, moving the armature from the adjusting position to an operating position to place the contact portion of the armature in a position disposed between the make and break contact surfaces and the gauging portion in a position removed therefrom, and forming a seal in said other end of the housing to mount the armature on said other end of the housing in said operating position. 7. The method set forth in claim 6 in which the step 25 of moving the armature from the adjusting position to the operating position comprises moving the armature generally along the axis of the elongated housing in a direction away from the make and break contact surfaces.

30 References Cited UNITED STATES PATENTS 3,242,557 3/1966 Ellwood 29-622 3,310,863 3/1967 Ellwood et a1 29-622 35 JOHN F. CAIMPBELL, Primary Examiner.

R. W. CHURCH, Assistant Examiner. 

